FCP X: Delete Generated Media

Posted on by Larry

Logo-FCPX.jpgFinal Cut Pro X handles render files and other generated media differently than Final Cut Pro 7. Let me explain.

Definition: Generated Media. Media created by Final Cut. This includes render files, optimized media and proxy media.


FCP 7 did not have the concept of optimized or proxy media. Yes, AVCHD files would be converted using Log and Transfer to ProRes 422, but, in general, you edited what you shot.

When it comes to render files, Final Cut 7 and Final Cut X both create render files for transitions, titles and effects, including color correction. However, once those files are created, the differences begin.

In Final Cut Pro 7, when you deleted or trimmed a clip to which render files were attached, those render files were immediately deleted. The advantage to this was that you never had render files hanging around not being used, but taking up storage.

While this saves a storage space, it also meant that you were often re-rendering clips that had already been rendered.


FCP X allows creating both optimized and proxy media for a wide variety of reasons, but, in general, they boil down to two:

As a fast estimate, assume that one minute of optimized media takes 1 GB to store, while one minute of proxy media takes about 250 MB to store.

However, FCP X significantly differs from from FCP 7 when it comes to render files.

In FCP X, render files are not deleted when you decide to remove a clip from the Timeline, or trim a portion of a clip, that has already been rendered. Instead, Final Cut Pro X hangs on to render files so that if you add that clip back to the timeline, or readjust the trim to a clip, it instantly reattaches the render files, so that no new rendering needs to be done; assuming there were no changes to the clip since the last time it was used.

NOTE: If Final Cut needs to re-render a clip, any existing render files for the frames being re-rendered are deleted.



Apple made it easy for us to manage generated media using File > Delete Generated Library/Event/Project Files. Final Cut determines which menu to display based upon what you have selected before going to the File menu.


In all three cases, this dialog appears.

If you realize, too late, that you should not have deleted either the optimized or proxy files, re-create them by selecting the clips you want to use in the Browser and choose File > Transcode Media.  Again, all you lose is time.


Give the amount of storage media often required, deleting generated files sounds like a good idea. In general, though, I don’t worry about this, unless I’m desperately short on storage space.

However, I DO delete generated media when archiving a project. There’s no reason to archive files that Final Cut can easily recreate when it needs them in the future.

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33 Responses to FCP X: Delete Generated Media

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  1. Lorne Ould says:

    I must say, I contacted coremelt, they sent me new updates, and correct registration info.
    Probably the best customer service next to Larry Jordan.
    All is corrected, aside from having to do a complete reinstall, and reintegration of where the original plugins were being utilized.
    Thank You to all that assisted.
    Best of luck in any of your endeavours !
    Lorne Ould

  2. mike cook says:

    Hi Larry,

    Does deleting optimized media effect the quality of the final shared project/output. or are those optimized files there simply to make editing easier?

    I have a long master project that is broken into smaller projects. When done with each project, I’m thinking to delete generated media to gain HDD space, but I’m worried that when I put them all together will they now have a lowed finished quality final output.


    • Larry says:


      The answer depends upon the codec/format of your camera master. If you shot H.264 or HEVC, optimized files will look better in a color grade because ProRes is 10-bit, while H.264 and HEVC are almost always 8-bit.

      However, in general, deleting optimized files at the end of a project won’t hurt anything because, if FCP X needs them, it will simply recreate them.


      • Mat says:

        I have to disagree in part with Larry here. Your generated media can never look better than the source material – if what you shot was 8 bit H.264, of 50i, or whatever, Transcoding to ProRes will basically just take up more space (and less processor time to work with). It can’t improve what you shot. While Larry is correct in saying that FCPX will simply regenerate optimised files if it needs them again, those optimised files merely help you edit, and possibly render out, faster.
        I haven’t done any side-by-side testing, so I’m open to correction if anyone has observed any witchcraft going on with respect to this.

        • Larry says:


          You are correct if you make no changes to your media during the edit. ProRes will only look as good as your camera master.

          Where ProRes can help – aside from improving render speed and editing efficiency – is in color grading, dissolves and other use of gradients. Because ProRes is 10-bit it provides 1024 gray-scale and color values per pixel, rather than the 256 values of 8-bit video, such as H.264.


  3. Jim says:

    Larry really helpful words. Thanks for this. I’m just endeavouring my first month on FCP and between you and Tom Wolsky from FCP forum it’s been great finding my way through rising hurdles and user lack of knowledge. Thanks again.

  4. sally bunter says:

    Help! FCPX project when exported to Master file drops some of the audio in the finished mov. Would deleting the generated media files help? Any other thoughts?

    • Larry says:


      Make sure you are exporting all roles, that all clips are enabled. If both are true, deleting generated media will help, but, it is more likely that something else is wrong.


  5. Shaun says:

    Hey Larry!

    I’m on an 18-core machine and creating optimized media takes no time, and I find that the exports are obviously much faster to ProRes 4444 when I have optimized media. I work on a lot of projects I don’t need to re-open, so the question is, is there a way to automatically delete generated media upon closing a project / closing FCPX?

    • Larry says:


      Keep in mind that “Optimized Media” is always ProRes 422. There’s no real benefit to ProRes 4444 if you are exporting media shot by a camera that wasn’t originated as raw or log files, or created on the computer.

      And in answer to your question, No. Sorry.


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